Locking attachment plug



June 2, 1936. ZURCHER 2,042,491

LOCKING ATTACHMENT PLUG Filed Jan. 27, 1934 Patented June 2, 1936 UNITED STATES LOCKING ATTACHMENT PLUG Ernest Zurcher, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application January 27, 1934, Serial No. 708,573

4 Claims.

ticularly to attachment plugs whose members are adapted to be locked to, and unlocked from, one 5 another.

It is an object of this invention to provide a separable plug whose members are locked by a relative longitudinal movement and unlocked by a relative rotary movement of the members.

It is a further object to provide a separable plug whose members are locked when projections on the spring contacts of one member engage openings in the blade terminals of the other member and are unlocked when the projections are moved )5 out of the openings.

It is an additional object to provide a plug construction which prevents the blade terminals from giving the spring contacts a permanent set when the members are being locked and unlocked, thus insuring both a positive electrical connection and a positive locking engagement between the spring contacts and blade terminals.

Other objects of the invention will become apparent upon reference to the following descrip- 25 tion and to the accompanying drawing, in which Fig. 1 is a view in perspective showing the body member; Fig. 2 is a view in perspective showing the cap member; Fig. 3 is a sectional view showing, the cap and body members in locked position; 30 Fig. 4 is a sectional view along the line 4-4 of Fig. 3; Fig. 5 is a similar view to Fig. 3 showing the cap and body members in unlocked position; Fig. 6 is a view in perspective showing the details of a spring terminal of the cap member, and Fig. 35 '7 is a view of the interior of one end of the cap. Referring now to the drawing, the attachment plug comprises a body member I and a cap member 2, both of which are constructed of any suitable material, such as a suitable molding com- 40 pound, hard rubber or porcelain. The attachment plug, forming the subject 01. the present invention, may be used in connection with the control unit of an electric refrigerator. The body member is accordingly illustrated as one end of 5 such a unit. It is to be understood, however, that the illustration of this use is merely by way of example, for the plug has other uses that will readily suggest themselves to those skilled in the art.

Proceeding now with the description, the body member I is provided with two terminal blades 3 each having an opening 4 and a bevelled outer end 5. In the drawing each terminal blade is shown bevelled on both faces, but it is necessary 55 to bevel only that facewhich engages thespring contact, i. e., the outside face of each terminal blade in the present example. A raised portion 6, integral with the body member 1, is provided with openings 1 through which the terminal blades 3 project into the interior of the body member. The terminal blades 3 may be attached in any suitable manner to the body member. In the example illustrated, the left-hand terminal blade 3 has integral therewith a terminal plate (not shown) positioned on the inside of the control unit box and fastened thereto by a screw I; while the right-hand terminal blade 3 is extended into the interior of the box to which it is fastened by a binding screw (not shown). The connections between the terminal blades and the control unit box form no part of the present invention, and accordingly these connections are not shown.

The cap member 2 is provided with a cover 9 of insulating material which fits into a recess in the attachable end of the cap. This cover, which is provided with two openings 1 I, is fastened to the cap member by means of screws l threading intoopenings in the cap member. Upon coupling the cap with the body member,the raised portion i of the body member is positioned within the recess formed by the side walls of the cap member and the cover 9, and when thus positioned serves to align the cap and body members and also to guide the rotary movement required to unlock the members. i

The cap member is provided with two similar longitudinal recesses I2 and I3, see Fig. 4. It is 1 preferred, though not necessary, to provide each recess with a flared side l4 so that the recess is wider at one than at the other end. The recesses may be rectangular in section or may be of any other shape so long as they are wider than the blade terminals and will permit the rotary movement of the blade terminals necessary to unlock the plug members. Adjacent to the top of each recess is a transverse recess, l or ii, Fig. 7. Each of these recesses has positioned in an opening therein a threaded metal insert ll. adapted to receive a binding screw I1 and each recess communicates with its associated longitudinal recess and with an opening i8. The opening II is a continuation of a central opening is in the non-attachable end of the cap member. Conductors (not shown) are carried through the opening l9 and connected to the metal inserts by the binding screws.

Disposed in each of the longitudinal recesses l2 and I3 is a spring contact [9; Referring to Fig. 6, each contact, which is formed of thin sheet metal having sufficient resiliency to give it a spring action, comprises a single V-shaped piece of metal having a ridge 20 and the straight sides 2| and 22. From the side 22 a portion 23 extends outwardly at right angles to the plane of the side and this portion is provided with an opening 24. In the side 2|, which serves as the contact arm, there is provided a projection 25 having a curved face and an abrupt shoulder 25'. Each spring contact is disposed in a longitudinal recess |2 or I3, with its ridge 20 uppermost, its projection 25 facing the flared or inner side of the recess and its portion 23 extending into the associated transverse recess |5 or IE and riveted to the metal insert |l therein with the opening 24 positioned above the opening in the metal insert. The free end of contact arm 2| extends toward the bottom of the recess. With this construction it is possible to provide greater spring tension for the contact arm than would be possible if the free end of the contact arm extended toward the upper end of the recess. Also, when the blade 3 is in the position shown in Fig. 4, a pull exerted on the blade will tend to increase the spring tension of the contact arm and improve the operation of the plug. The spring contacts |9 are thus in electrical connection with the conductors (not shown) connected to the metal inserts When the cap member is coupled to the body member, the bevelled end 5 of the blade terminals 3 first engages the side 2| of the spring contacts, thereby forcing this side toward the outside edge of the recesses l2 and I3; the bevelled ends next engage the projections 25 of the spring contacts, thus forcing the sides 2| away from the blades; and finally the raised portion 6 of the body member enters the recess formed by the side Walls of the cap member and the cover 9, aligning the members, and the projections 25 of each spring contact snap into the openings 4 of the associated blade terminals with the abrupt shoulder 25' engaging one side of the openings, as shown in Fig. 4, thus locking the cap and body members against accidental separation. It is to be noted that the longitudinal recesses l2 and I3 are wider than the terminal blades 3 and that as the blades are positioned nearer one than the other end of these recesses there is sufficient space between the blades and the other end of the recesses for effecting the rotary movement of the terminal blades necessary to unlock the members. It is also to be noted that the bevelled outer faces of the terminal blades 3 prevent the sides 2| of the spring contacts from receiving a permanent set if the blade terminals are pushed into the openings with a rapid movement.

To unlock the cap and body members, the cap member 2 is turned in a counter-clockwise direction about the raised portion 6 of the body member which guides the movement. The rotary movement thus imparted to the blade terminals 3 causes the portion of each'blade defining one of the openings 4- to ride upon the curved face of the projections 25 on the spring contacts. The blade terminals continue to ride upon the projections until the blades reach the position shown in Fig. 5, when further rotation of the blades is prevented by their engagement with the sides of the openings II in the cover 9. It is preferred to thus limit the rotary movement of the blades in order to prevent the sides 2| of the spring contacts from receiving from the terminal blades a permanent set which would thereafter prevent the blades and contacts from making positive the members.

electrical connection and positive locking engagement. When the blades reach the position shown in Fig 5 they have obviously moved through a distance sufficient to force the projections 25 out of the openings 4 of the blades and the cap and body members can then be separated by a relative longitudinal movement of the blades and contacts. It is to be noted at this point that the blades and contacts can be unlocked by a relatively slight rotary movement.

It is evident that the blades and spring contacts may be interchanged and the cap and body members unlocked by a counter-clockwise movement of the body member rather than the cap member and also that the direction in which either plug member is rotated to unlock the members may be reversed.

From the foregoing description it is apparent that the invention provides a separable attachment plug whose members can be locked by a relative longitudinal movement of the members and unlocked by a slight relative rotary movement of The invention furthermore provides a separable attachment plug in which the spring contacts are prevented from receiving a permanent set from the blade terminals when the plug members are being locked and unlocked, thereby insuring positive electrical contact and positive locking engagement between the contacts and blades. And finally, the invention provides a separable attachment plug having its members aligned, and the rotary movement necessary to unlock the members guided, by the cooperation of a raised portion on one member and a recess in the other member.

The present invention is not to be restricted to the particular form or arrangement of parts herein shown and described, as it is apparent that they may be changed and modified without departing from the scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A separable attachment plug comprising a first member provided with a blade terminal having an opening therein, a second member provided with a cooperating recess for receiving said terminal, the dimensions of said recess and said terminal being such as to permit relative rotary movement of said members about the axis of the plug, and a spring contact disposedin said recess having a free end extending toward the bottom of said recess, said contact being biased toward said terminal and having a laterally curved projection thereon having an abrupt shoulder at the lower end adapted to enter the opening in said terminal when said terminal is inserted in said recess to lock said members against separation by relative longitudinal movement, the laterally curved surface of said projection providing a surface on which the edges of the opening in the blade slide to force the projection out of the opening and unlock the members when said members are rotated relative to one another about the axis of the plug.

2. A separable attachment plug comprising a first member provided with a blade terminal having an opening therein, a second member provided with a cooperating recess for receiving said terminal, the dimensions of said recess and said terminal being such as to permit relative rotary movement of said members about the axis of the plug, a V-shaped spring contact disposed in said recess having its ridge at the top of said recess and having its sides extending toward the bottom of said recess, one of said sides providing a contact arm, and a laterally curved projection on said contact arm having an abrupt shoulder at the lower end adapted to enter the opening in said terminal when'said terminal is inserted in said recess to lock said members against separation by relative longitudinal movement, the laterally curved suriacepf said projection providing a surface on which the edges of the opening in the terminal slide to force the projection out of the opening and unlock the members when the members are rotated relative to one another about the axis of the plug.

3. A separable attachment plug comprising a first member provided with a blade terminal having an opening therein, a second member provided with a cooperating recess for receiving said terminal, the dimensions of said recess and said terminal being such as to permit relative rotaiy movement of said members about the axis of the plug. and a spring contact disposed in said recess having a free end extending toward the bottom of said recess, said contact being biased toward said terminal and having a projection thereon having an abrupt shoulder at the lower end adapted to enter the opening in the terminal when the terminal is inserted in said recess to lock said members against separation by relative longitudinal movement, said contact and said terminal being provided with 00- operating surfaces whereby relative rotation of said members forces said projection out of the opening to unlock said members.

4. A separable attachment plug comprising a first member provided with a blade terminal having an opening therein, a second member provided with a cooperating recess for receiving said terminal, the dimensions of said recess and said terminal being such as to permit relative rotary movement of said members about the axis of the plus. a V-shaped spring contact disposed in said recess having its ridge at the top of said recess and having its sides extending toward the bottom of said recess, one of said sides providing a contact arm, and a projection on said contact arm having an abrupt shoulder at the lower end adapted to enter the opening in said terminal when said terminal is inserted in said recess to lock said members against separation by relative longitudinal movement, said contact and said terminal being provided with cooperating surfaces whereby relative rotation of said members forces said projection out of the opening to unlock said members.

ERNEST ZURCHER. 

